Process for the preparation of charged thermosetting compounds of the polyurethane type and compounds obtained thereby

ABSTRACT

Process for the preparation of filled heat-curable compounds of the polyurethane type by reaction of condensation of the constituents of the desired compound in the presence of a pulverulent filler, which is characterized in that the said filler is predispersed in the presence of a stabilizing agent in a liquid organic phase compatible with the desired heat-curable compound in the course of its formation reaction, the said filler being then in the form of a homogeneous and stable suspension, and the suspension thus prepared is then introduced into the reaction mixture before, during or after the introduction of at least one of the constituents of the desired heat-curable compound. 
     The process according to the invention makes it possible to produce compounds of the polyurethane type whose mechanical and physical characteristics are at least equivalent or even improved in relation to those of the unfilled identical compounds by virtue of the excellent distribution of the inorganic filler.

FIELD OF THE INVENTION

The invention relates to a process for preparation of filledheat-curable compounds of the polyurethane type by condensation reactionof their constituents in the presence of a pulverulent filler.

The invention also relates to the filled heat-curable compounds of thepolyurethane type obtained according to the process.

The invention finally relates more particularly to the filled foamedheat-curable compounds of the polyurethane type obtained according tothe process.

BACKGROUND OF THE INVENTION

For a long time specialist literature has described many heat-curablecompounds filled with pulverulent inorganic materials of preferablypigment-like size and the processes for obtaining them, which concernboth foamed and unfoamed filled heat-curable compounds, which in thefirst case are in the form of plastic masses containing fine gaseousinclusions.

The introduction of inorganic fillers (French patent 2,531,971) into thevarious heat-curable compounds of the polyurethane type is directed atvarious objectives in order to respond to demands of specialist or userindustries, such as, for example, the motor vehicle, building,electronics, electrical domestic appliances or other, industries, foravailability of nonmetallic products with specific characteristics suchas lightness, rigidity, reduced shrinkage, decrease in the expansioncoefficient, improvement in thermal shock resistance, improvement insound insulation, sufficient flexural, tensile, compressive mechanicalstrength or other major physical characteristics.

Various fillers intended for heat-curable compounds of the polyurethanetype are referred to in "European Plastics News" (1979, August, page 21)and "Modern Plastic International" (1982, April, page 42), such ascalcium carbonate, talc, mica, aluminium trihydrate, silica, but alsoglass fibres, textile fibres or others. Thus, in the RIM (ReactionInjection Moulding) and RRIM (Reinforced Reaction Injection Moulding)processes fillers as diverse as glass fibres, ballotini, mica,wollastonite, talc and treated inorganic fibres are often used in orderto increase the rigidity of the articles produced and to reduce theircost ("Plastic Technologic" 1978, November, page 13 and "Elastomerics",1979, February, page 25).

Various processes are proposed for performing the introduction offillers into heat-curable compounds, the essential preoccupation ofwhich is to produce filled heat-curable compounds which have at leastsome of the specific characteristics referred to above.

In a first type of process the filler is introduced into one of theconstituents of the polyurethane compound, generally the polyol. Tostabilize the suspension thus prepared, that is to say to avoidsedimentation effects, the polyol is frequently subjected to grafting(DE OS 2,654,746, 2,714,291 and 2,739,620), with methacrylic acid orwith another vinyl compound such as styrene, or else with isocyanate (DEOS 2,834,623). However, experimental results show that the suspensionthus prepared does not escape either a considerable increase in itsviscosity, which makes it difficult to handle, or a poor distribution ofthe filler within the heat-curable compound produced.

According to a second type of process, and to try and get rid of thedisadvantages revealed in the first type, the filler is surface-treatedbefore its introduction into one of the constituents of the desiredheat-curable compound (the polyol), by means of a coating agent which iscompatible with the constituents, a coating agent which is, for example,a C₈ to C₁₄ alcohol (FR 2,531,971). However, this type of processproduces disadvantages which are substantially identical with thosereferred to earlier, since the user still finds an increase in theviscosity of the suspension of the filler in the polyol, attenuated tobe sure, but still too high, which causes nonuniform dispersion of thisfiller in the heat-curable compound which is subsequently formed.

In another type of process, which is directed towards the production ofunfoamed filled heat-curable compounds (intended to becompression-moulded), the process consists in preparing (for exampleaccording to FR 1,512,029) a mixture consisting of the filler and of thenecessary additives such as lubricants, condensation catalysts,optionally colouring substances and plasticizers and in then introducinginto this mixture, which is being stirred vigorously, the heat-curableresin or its initial constituents, in well-defined quantities andproportions.

However, the heat-curable compounds thus produced exhibit the samedisadvantages as those already referred to, which result from anonuniform dispersion of the filler within the said compounds.

According to another type of process which is directed more towards theproduction of filled foamed heat-curable compounds, the filler and theplasticizer are introduced separately into the mixture of theconstituents of the desired heat-curable compound. A process of thistype (described for example in JP 56-155,232 or ES 371,150) results infoamed heat-curable compounds of the polyurethane type in which thecells are formed nonuniformly and are consequently embrittled by thepoor filler dispersion.

Thus, it appears that a real and serious problem exists as soon asfillers, in particular inorganic ones, are introduced into polyurethaneheat-curable compounds, since these filled compounds exhibitunacceptable physical anomalies.

In the case of unfoamed filled polyurethane compounds the physicalanomalies revealed by differences from these same compounds unfilledare, for example, not only the increase in the density and in therigidity, but also the weakening in mechanical characteristics such asreduced tensile, flexural and compressive strength.

In the case of filled and foamed polyurethane compounds, physicalanomalies revealed in the first group also manifest themselves, with theadditional appearance of phenomena such as the increase in the densityof the filled compound, in its heterogeneous hardness to the touch, innonuniformity of flexibility and in mechanical characteristics which arerapidly weakened by the application of repeated deformation cycles(hysteresis). All these phenomena are linked, as the Applicant Companyhas been able to ascertain, with a poor dispersion of the filler withinthe desired heat-curable compound.

Lastly, added to all these ills are phenomena of increase in theviscosity of the medium receiving the filler or of sedimentation of thesaid filler in industrial plants, phenomena which prejudice their goodoperation and the quality of the heat-curable compounds to be marketed.

Consequently, the problem of the utilization of the fillers in theheat-curable compounds of the polyurethane type remaining in itsentirety, it is understandable that their use in these compounds is verylimited.

Thus, where the polyurethanes are concerned, the objectives which theinvention is aimed at are to prevent the increase in the viscosity ofthe constituent or of the mixture of the constituent of the desiredheat-curable compound receiving the inorganic filler; to prevent thefiller sedimentation phenomena in industrial plants suitable for theproduction of the desired heat-curable compound; to permit theintroduction of the filler into one of the constituents orsimultaneously with all the constituents or else in the mixture of theconstituents of the desired heat-curable compound; finally, to producean excellent distribution of the inorganic filler within the desiredheat-curable compound, in order to provide it with an appreciableimprovement in its physical and mechanical properties andprocessability, while increasing the quantity of filler which isintroduced.

SUMMARY OF THE INVENTION

Aware of the abovementioned disadvantages, the Applicant Company hassought, through its research, to establish a process for the preparationof filled heat-curable compounds of the polyurethane type meeting theobjectives which it set itself.

The process according to the invention for the preparation of filledheat-curable compounds of the polyurethane type by reaction ofcondensation of the constituents of the desired compound in the presenceof a pulverulent filler is characterized in that the said filler ispredispersed in the presence of a stabilizing agent in a liquid organicphase compatible with the desired heat-curable compound in the course ofits formation reaction, the said filler being then in the form of ahomogeneous and stable dispersion, and the suspension thus prepared isthen introduced into the reaction mixture before, during or after theintroduction of at least one of the constituents of the desiredheat-curable compound.

DETAILED DESCRIPTION OF THE INVENTION

While the prior art recommends processes for the preparation of filledheat-curable compounds which comprise the introduction of the fillerinto the reaction mixture without previous preparation, or else after asurface treatment, processes which result in obtaining filledheat-curable compounds whose mechanical and physical characteristics arestill diminished, the process according to the invention isdistinguished therefrom by the fact that the filler introduced into thereaction mixture is introduced in the form of a homogeneous and stablesuspension of the said filler in a liquid organic phase compatible withthe desired heat-curable compound, that is to say compatible with atleast one of the constituents of the desired heat-curable compound andduring the reaction of formation of the said heat-curable compound.

According to the invention the liquid organic phase compatible with thedesired heat-curable compound is chosen from plasticizers for theheat-curable compounds of the polyurethane type and desirably from thegroup consisting of symmetrical or unsymmetrical aliphatic, aromatic,cyclic, branched or unbranched dialkyl phthalates or glycol derivatives,used by themselves or mixed, such as, for example, dioctyl phthalate,dibutyl phthalate, dinonyl phthalate, didecyl phthalate, diheptylphthalate, diisodecyl phthalate, diisoundecylenic phthalate, mixedoctyl, butyl and decyl phthalates, benzyl phthalate, cyclohexylphthalate, methoxyethyl phthalate, methoxybutyl phthalate, butoxyethylphthalate and other glycol-based substituents, organic or inorganicpoly- or monoacidic esters of the alkyl adipate or alkyl sebacate type,diesters of C₁ to C₈ alcohols of mono-, di- or triethylene glycol and ofglycerol of the trimellitate, azelate, abietate, citrate, mellitate,stearate, oleate, palmitate, ricinoleate, myristate, benzoate, orpelargonate type, mono- or polyalkyl and aryl phosphates and glycolderivatives such as, for example, trioctyl phosphate, tricresylphosphate, octyldicresyl phosphate, or others, alkylaryl phosphates,polyesters such as, for example, ethylene glycol or propylene glycolpolyadipates, ethylene glycol or propylene glycol polysebacates andcondensed halophosphates.

The pulverulent filler to be predispersed within the abovementionedliquid organic phase and taking part in the process according to theinvention for the preparation of filled heat-curable compounds of thepolyurethane type is made up of pulverulent substances of inorganic orsynthetic origin.

The pulverulent inorganic substances forming part of the filler arechosen, for example, from inorganic salts and/or oxides such as calciumcarbonate, magnesium carbonate, zinc carbonate, dolomite, lime ormagnesia; aluminium trihydroxide; silica; clays and othersilicoaluminous materials such as kaolin, talc or mica; metallic oxides,such as, for example, zinc oxide, antimony trioxide, iron oxides,titanium oxide, wollastonite, glass fibres and ballotini, variouspigments and red phosphorus.

The filler can also be made up of organic pulverulent substances ofnatural or synthetic origin such as, for example, colorants, carbonblack, starch, cellulose fibres and flour, carbon fibres and variousagents known for their specific actions, such as, for example, melaminepowders.

All these pulverulent substances can be used in the filler by themselvesor in combination according to the desired heat-curable compound.

The pulverulent substances employed in the invention have a dimension ofbetween 0.01 and 300 μm and more preferably between 0.1 and 100 μm.

The stabilizing agent used for the preparation of the homogeneous andstable suspension of the filler in the liquid organic phase compatiblewith the desired heat-curable compound corresponds to the generalformula containing at least one free acidic functional group: ##STR1##in which (A) denotes ethylene oxide, (B) denotes propylene oxide, with0≦(m+n)≦24, R is an alkyl radical, an aryl radical, an alkylarylradical, a saturated or unsaturated heterocyclic ring containing from 5to 28 carbon atoms and preferably from 8 to 24 carbon atoms, oralternatively a steroid radical, it being possible for the said radicalR to be branched or unbranched and/or to contain one or more functionalgroups of the halogen --OH, --COOH, --COOR, --NO₂, --NH₂, --CONH₂, CN,phosphinic, phosphonic, phosphoric, sulphonic or sulphuric type, while Xcan be one of the carboxylic, phosphinic, phosphonic, phosphoric,sulphonic or sulphuric radicals.

In the case where X contains a number of acidic functional groups, atleast one of these must remain free, it being possible for the others tobe converted into salts or esterified by means of an alcohol of formulaR' --OH in which the radical R' may be a carbon chain containing 1 to 4carbon atoms or one of the radicals belonging to the group defined abovein the case of R. It is also possible for the radical R' to be identicalwith the radical R.

By way of example, which may be mentioned radicals in the case ofradical R are as diverse as normal or iso hexyl, octyl, decyl, dodecyl,dodecyldioxyethylene, tetradecyl, hexadecyl, hexadecyltrioxyethylene,octadecyl, octadecyloxyethylene, octylpentaoxyethylene, heptadecyl,phenyl, 2-methyl-2-butyl, 2-methyl-1-butyl, 3-phenyl-1-propenyl,1-phenylpropenyl, para-nonylphenyl dioxyethylene, para-methylphenyl,cyclohexyl, the cholesterol radical, β-naphthyl and diol radicals.

Various adjuvants of known type and commonly employed in the productionof heat-curable materials of the polyurethane type can also beintroduced, either into the stable and homogeneous suspension of thefiller or into the constituents of the desired heat-curable compound, orelse simultaneously partly into the suspension of the filler and partlyinto the constituents of the desired heat-curable compound.

These various adjuvants are, for example, heat or photochemicalstabilizers, lubricants, plasticizers other than those used in thepreparation of the filler suspension, antistatics, flame-retardants,metal-passivating agents such as copper-passivating agents, blowingagents, reaction catalysts, surfactants, or still others.

It is also possible, as soon as the pulverulent filler is dispersedwithin the liquid organic phase compatible with the desired heat-curablecompound according to the invention, to add thereto at least a fractionof at least one of the polyols capable of taking part in the productionof the said heat-curable compound.

In practice, the preparation according to the invention of the stableand homogeneous suspension of the pulverulent filler in the liquidorganic phase is carried out by using processes and means which areknown to the specialist.

It can be carried out, for example, at room temperature in a mixerfitted with stirring means by the successive introduction of the liquidorganic phase, of the stabilizing agent and of the filler.

According to the invention, the stable and homogeneous suspension of thepulverulent filler in the liquid organic phase is composed chiefly, inrelation to the total mass:

a) of 20% to 80% by weight, and preferably from 40% to 70% by weight ofthe filler,

b) of 79.9% to 18.4% by weight and preferably from 59.5% to 28.9% byweight of the liquid organic phase,

c) of 0.1% to 1.6% by weight, and preferably of 0.5% to 1.1% by weightof the stabilizing agent.

The viscosity of the stable and homogeneous suspension of thepulverulent filler is desirably between 500 and 2,000 mPa.s andpreferably between 600 and 1,800 mPa.s, in order to be compatible withthat of the polyols employed in the composition of the desiredheat-curable compound of the polyurethane type. This viscosity ismeasured at room temperature by means of a Brookfield apparatus fittedwith a number 3 or 4 spindle according to the viscosity to be measured;it is measured at a speed of 100 revolutions per minute.

According to the invention, as soon as the homogeneous and stablesuspension of the filler in the liquid organic phase is produced, thesuspension is introduced in the initial composition of the desiredheat-curable compound of the polyurethane type, comprising at least onepolyol or an organic constituent containing a mobile hydrogen, at leastone polyisocyanate, optionally a foaming agent, a catalyst andoptionally other agents.

The stable and homogeneous suspension of the filler is introduced intothe initial composition of the desired heat-curable compound of thepolyurethane type in a proportion of 1% to 100% by weight and preferablyof 10% to 50% by weight relative to the polyol used.

While it is known that the introduction of a filler (in a givenquantity) into a polyol results in a very large increase in theviscosity of the filled polyol when compared with that of the polyolalone, the introduction of the same quantity of the said filler into thepolyol in the form of the stable and homogeneous suspension according tothe invention makes it possible to keep the viscosity of the polyol thusfilled close to the initial viscosity of the said polyol alone, or evento reduce it.

The polyols used according to the invention are well-known constituentswhich belong to the groups of the polyethers and of polyesters.

Among the common polyol polyethers there may be mentioned, for example,the products of the addition of propylene oxide to a simple polyol suchas, for example, glycol, glycerol, trimethylolpropane, sorbitol, in thepresence or absence of ethylene oxide. However, special polyolpolyethers may also be mentioned, such as, for example, aminated-basepolyethers obtained by the addition of propylene oxide or optionallyethylene oxide to amines, halogenated polyethers and grafted polyethersresulting from the copolymerization of styrene and of acrylonitrile insuspension in a polyether, or else polytetramethylene glycol.

Among the polyol polyesters there may be mentioned, for example, thoseresulting from the polycondensation of polyalcohols with polyacids ortheir anhydrides, such as diacids, such as, for example, adipic,phthalic or other diacids, reacting with diols (for example ethyleneglycol, propylene glycol, butylene glycol or others); triols (forexample, glycerol, trimethylolpropane or others), and tetrols (forexample, pentaerythritol or others, by themselves or mixed).

However, among the polyols there may also be mentioned varioushydroxylated compounds such as, for example, hydroxylatedpolybutadienes, prepolymers containing hydroxyl end groups (resultingfrom the reaction of an excess of polyol with a diisocyanate), or elsesimple polyols such as, for example, glycerol, amino alcohols used in asmall quantity with polyol polyethers or polyol polyesters to increasethe crosslinking.

The polyisocyanates used according to the invention are also well-knowncompounds of aromatic type, such as, for example, toluene diisocyanate(TDI), 4,4'-diphenylmethane diisocyanate and its homologues (MDI),1,5-naphthalene diisocyanate (NDI), or of linear type such as, forexample, hexamethylene diisocyanate (HDI), isophorone diisocyanate(IPDI) or else those taking the form of prepolymers obtained by thecombination of isocyanates with each other or with reactive compounds.

Foaming agents for the heat-curable compound of the polyurethane typecan also be used. They are chosen from those which are well known suchas, for example, water, which reacts with the --NCO radicals releasingcarbon dioxide, or else fluorine-containing liquids and gases such astrichlorofluoromethane, dichlorofluoromethane or other fluoroalkanes, aswell as various hydrocarbons, in particular halogenated ones such as,for example, dichloromethane.

For the reaction of formation of the desired heat-curable compound to bebalanced it is desirable to introduce into the reaction mixture asuitable catalytic system made up of at least one catalytic component.Among the catalytic components used may be mentioned, for example,tertiary amines, triethylamine, N-methylmorpholine, substitutedbenzylamines, diaza[2.2.2]bicyclooctane, or else tin compounds such as,for example, dibutyl tin dilaurate, stannous octanoate, or else organicsodium, potassium or calcium salts, for example.

Finally, various other adjuvants of known type can also be introducedinto the composition of the desired filled heat-curable compound. Thesevarious possible adjuvants belong to the groups of surface-activeagents, (for example, siloxane-alkylene oxide block polymers,sulphonates, nonionic surfactants), flame-retardant agents involved inthe structure of the macromolecular chains (for example by incorporationof nitrogen, phosphorus, chlorine or bromine atoms in the saidstructure), pigments and colorants and demoulding agents, crosslinkingagents such as polyamines, ethylenediamine or others.

The filled heat-curable compound of the polyurethane type is obtained,generally, at room temperature, by mixing the homogeneous and stablesuspension of the filler:

either by first of all forming a premix of the said suspension with thepolyol, this premix being then mixed with the other constituents,

or simultaneously, with the various constituents of the desiredheat-curable compound,

or, finally, after the premix of the constituents has been produced,

all the constituents used being introduced in quantities and proportionsdefined in the application.

It may be desirable to modify the relative proportions of the variousconstituents of the formulation in order to increase the density of themacromolecular network and thereby some mechanical properties (forexample compressive strength). More particularly, it may be desirable toincrease the "isocyanate value" (which is the percentage ratio of theisocyanate content used in the formulation to the theoretical contentrequired) as is usually practised by the specialist.

The filled heat-curable compounds of the polyurethane type according tothe process of the invention can be produced by known means, for exampleby injection, by casting or by spraying, the various components involvedin the reaction being metered, for example, using metering (gear orplunger) pumps and mixed in a mixing head to form the compositionemployed using the above-mentioned means.

In this way, it is possible to produce filled heat-curable compounds ofthe unfoamed polyurethane, elastomeric polyurethane or else rigid,semirigid or flexible foamed polyurethane type without producing, at thetime of the introduction of the filler, an increase in the viscosity ofthe reaction mixture made up of the various constituents and agentsused, nor the appearance of filler sedimentation phenomena in industrialplants.

More than that, and by virtue of the invention, it is possible toperform the introduction of the filler into one of the constituents, orsimultaneously with all the constituents, or else into the mixture ofthe constituents of the desired heat-curable compound, while obtainingan excellent distribution of the inorganic filler within it and anappreciable improvement in its mechanical and physical properties and inprocessability while increasing the quantity of filler which isintroduced.

The process according to the invention can be applied using knowntechniques intended for the manufacture of heat-curable compounds of thepolyurethane type, for example in free foaming, in moulding in a cold orhot, open or closed mould or in others still.

The invention will be understood better by virtue of the illustrativedescription of the examples of preparation of suspensions of the fillerin the organic liquid phase and the dispersion of the filler within theheat-curable compounds of the polyurethane type.

EXAMPLE 1

This example illustrates the preparation of the homogeneous and stablesuspension of the inorganic filler of pigment-like size in a liquidorganic phase in the presence of a stabilizing agent.

To do this, the water-immiscible liquid organic phase, which isdiisoundecylenic phthalate (D.I.U.P.) was introduced into a preparationvessel fitted with a stirrer (fast disperser of a known type) in aproportion of 39.1% by weight relative to the mass of the suspension tobe prepared.

Next, the stabilizing agent, which is a phosphated oxyethylenated alkylof formula C₁₀ H₂₁ --(CH₂ --CH₂ --O)₅ --PO₂ H₂ (representing 1.5% byweight relative to the inorganic filler) was dissolved in the liquidorganic phase in a proportion of 0.9% by weight relative to the mass ofthe suspension to be prepared.

Finally, into the solution thus prepared was introduced the pulverulentinorganic filler of pigment-like size, consisting of natural pulverulentcalcium carbonate with a specific surface of 5.5 m² /g⁻¹, a meandiameter of 1 μm and a 6 μm cut, in a proportion of 60% by weightrelative to the mass of the suspension to be prepared.

At the end of its preparation, the suspension had a viscosity of 850mPa.s. After a storage period of 8 days it was possible to ascertainthat the prepared suspension was homogeneous and stable, since theviscosity measured at the end of preparation was the same and as nosedimentation phenomenon was observable.

By comparison, the introduction of 60% by weight of the same pulverulentinorganic filler (CaCO₃ with a specific surface of 5.5 m² /g, a meandiameter of 1 μm and a 6 μm cut) into 40% by weight of the same liquidorganic phase (DIUP) in the absence of the stabilizing agent results inthe formation of pasty mixture whose viscosity can no longer be measuredusing the Brookfield viscometer.

EXAMPLE 2

This example illustrates the preparation of the homogeneous and stablesuspension of the inorganic filler according to the invention,consisting of aluminium trihydroxides (marketed by Martinswerke underthe name OL 104), with a specific surface of 3 m² /g and a mean diameterof 2 μm in the liquid organic phase in the presence of the samestabilizing agent as in Example 1.

The preparation was carried out according to the same process as inExample 1 and according to the following proportions in % by weight:

    ______________________________________                                        aluminium trihydroxide   50%                                                  diisoundecylenic phthalate                                                                             49.5%                                                (D.I.U.P)                                                                     stabilizing agent:        0.5%                                                C.sub.10 H.sub.21 (CH.sub.2 --CH.sub.2 --O).sub.5 --PO.sub.3 H.sub.2          ______________________________________                                    

The viscosity of this suspension, measured at the end of itspreparation, was 1,240 mPa.s (measured in a Brookfield viscometer-RTVNo. 4 spindle, at 100 revolutions per minute at 23° C.).

No sedimentation phenomenon was observable after 8 days' storage.

EXAMPLE 3

This example illustrates the preparation of the homogenous and stablesuspension of an organic filler according to the invention, consistingof a pulverulent melamine (marketed by the Chemie Linz Company) in aliquid organic phase in the presence of the same stabilizing agent as inExample 1.

The preparation was carried out according to the same process as inExample 1 and according to the following proportions in % by weight:

    ______________________________________                                        Melamine                  70%                                                 Phosphated plasticizer marketed by                                                                      28.9%                                               Monsanto under the name Santiciser 148                                        Stabilizing agent          1.1%                                               C.sub.10 H.sub.21 (CH.sub.2 --CH.sub.2 --O).sub.5 --PO.sub.3 H.sub.2          ______________________________________                                    

The viscosity of this suspension, measured under the same conditions asin Example 2, was 6000 mPA.s. No sedimentation phenomenon was observableafter eight days' storage.

EXAMPLE 4

This example illustrates the observed effect of the minor modificationof the viscometric characteristics of a polyol filled by means of thestable and homogeneous suspension according to the invention bycomparison with the viscometric characteristics of the same polyol byitself and filled by the direct introduction of the same filler inpulverulent form, as indicated by the prior art.

The following were prepared in a manner similar to the preparationprocess described in Example 1:

In the case of a first series of tests (Test 1), a homogeneous andstable suspension of a pulverulent calcium carbonate marketed under thetrademark Millicarb by the Omya company by dispersing 50% by weight ofthe said filler in 49.5% by weight of dioctyl phthalate (liquid organicphase) with the aid of 0.5% by weight of a stabilizing agent of formula:

    C.sub.8 H.sub.17 (CH.sub.2 --CH.sub.2 --O).sub.5 --PO.sub.3 H.sub.2.

In the case of a second series of tests (Test 2), a homogeneous andstable suspension of a calcium carbonate marketed under the trademark"L'Etiquette violette" by the Omya company, by dispersing 49.5% byweight of the said filler in 50% by weight of diisoundecylenic phthalate(liquid organic phase) with the aid of 0.5% by weight of a stabilizingagent of formula

    C.sub.10 H.sub.21 (CH.sub.2 --CH.sub.2 --O).sub.5 --PO.sub.3 H.sub.2

The following were then prepared for the two series of tests:

the polyol filled with 25 parts of the pulverulent filler according tothe prior art in 100 parts of the said polyol,

the polyol filled with 50 parts of the homogeneous and stable suspensionaccording to the invention in 100 parts of the said polyol.

The Brookfield viscosities at 23° C. (RVT 2 spindle) were accordinglymeasured, in mPa.s at 50 revolutions per minute:

of the polyol by itself,

of the homogeneous and stable suspensions of the fillers according tothe invention

of the polyol filled with the pulverulent inorganic fillers (accordingto the prior art)

of the polyol filled with the homogeneous and stable suspensionsaccording to the invention.

The sedimentation and nonsedimentation characteristics of each of theabovementioned filled polyols were also checked.

The corresponding results have been assembled in Table 1 below:

                  TABLE 1                                                         ______________________________________                                        Introduction of 25 parts of filler into                                       100 parts of polyol.                                                          Viscosity in mPa.s.                                                                        Test 1     Test 2                                                ______________________________________                                        Polyol alone   430           430                                              polyurax polyol                                                               U - PPG                                                                       2025 from BP                                                                  Homogeneous and stable                                                                       300          660                                               suspension of the                                                             filler according to the                                                       invention                                                                     Polyol with pulverulent                                                                      Millicarb    Etiquette violette                                filler according to the                                                                      650          1100                                              prior art      complete sedi-                                                                             complete sedi-                                                   mentation    mentation after                                                  after 1 hour 1 hour thirty                                     Polyol with filler                                                                           400           580                                              according to the invention                                                                   No sedimentation after 2 days                                  ______________________________________                                    

EXAMPLE 5

This example illustrates the process according to the invention for thepreparation of filled heat-curable compounds of the polyurethane type bycondensation reaction of the constituents of the desired compound in thepresence of a pulverulent filler introduced in the form of thehomogeneous and stable suspension of Example 1.

To do this, the continuous manufacture of filled polyurethane foamblocks for cutting out was carried out in an industrial plant by castingon a conveyor belt.

A casting head driven in a transverse reciprocating motion deposited theliquid composition (mixture of the constituents and the filler) on to akraft paper with raised edges, supported by a first inclined conveyorbelt. After the foaming was initiated, the foaming polyurethanecomposition was picked up by a second horizontal conveyor belt, the rooffoaming (in the height direction) being controlled by virtue of thepresence of a kraft paper maintained by a series of rolls.

The constituents forming part of the composition for producing thefoaming polyurethane compound were introduced into the casting headusing metering pumps, the mixing being performed by mechanical stirring.

The compositions used in the manufacture of the foamed polyurethanecompound contained qualitatively the following constituents:

a polyether polyol with a molecular weight of 3,500 having available ahydroxyl number equal to 48 (expressed in milligrams of KOH per gram),

a plasticizer and the filler being in the form of the suspensionoriginating from Example 1,

a polyisocyanate, which is toluene diisocyanate (TDI 80-20 containing80% of 2,4-isomer and 20% of 2,6-isomer),

water as foaming agent,

well-known reaction catalysts such as diaza[2.2.2]-bicyclooctane(DABCO), dimethylethylamine (DMEA), or else stannous octanoate,

silicones well-known as surface-active agents,

colorants and various agents usually employed by the specialist.

The quantities of the various constituents, expressed in parts byweight, are given together in:

Table 2, when the compositions were employed on a machine adjusted to200 centimeters in width (Tests 3 to 6),

Table 3, when the compositions were employed on the same machineadjusted to 100 centimeters in width (Tests 7 to 10).

Similarly, all the mechanical and physical characteristics of thepolyurethane foams thus produced have been brought together in Tables 4and 5.

These characteristics were determined by means of the standardizedmethods which are listed below:

density, according to NF standard T56107

indentation hardness, according to ISO standard 2439 method B

compression remanence according to ISO standard 1856 method A

dynamic fatigue tests: height and hardness according to NF standardsT56114 and T56115

compressive strength, according to DIN standard 53 577

wet aging, according to NF standard T56117

tensile strength, according to ISO standard 1798

elongation at break, according to ISO standard 1798

resistance to air flow, according to NF standard T56127.

Inspection of Tables 4 and 5 shows that all the physical and mechanicalcharacteristics of the filled foamed polyurethanes produced according tothe process of the invention are very close, or even equivalent to thoseof the same unfilled foamed polyurethanes. It is consequently apparentthat the excellent dispersion of the filler within the polyurethanefoams makes it possible to produce heat-curable compounds withoutdeterioration in their mechanical and physical characteristics, thisbeing by virtue of the process of the invention.

                  TABLE 2                                                         ______________________________________                                        POLYURETHANE COMPOSITIONS FOR 200                                             CENTIMETRE MACHINE                                                                   TEST 3  TEST 4    TEST 5    TEST 6                                            in parts                                                                              in parts  in parts  in parts                                          by weight                                                                             by weight by weight by weight                                  ______________________________________                                        Polyol   100.00    100.00    100.00  100.00                                   Filler   0         15.00     20.00   25.00                                    suspension                                                                    Toluene  42.20     46.40     47.50   48.60                                    diisocyanate                                                                  Water    3.20      3.60      3.70    3.80                                     Catalyst 1                                                                             0.15      0.15      0.15    0.15                                     (DABCO)                                                                       Catalyst 2                                                                             0.30      0.30      0.30    0.30                                     (DMEA)                                                                        Catalyst 3                                                                             0.19      0.31      0.32    0.34                                     (stannous                                                                     octanoate)                                                                    Silicones                                                                              0.85      0.94      0.97    1.00                                     ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                        POLYURETHANE COMPOSITIONS FOR 100                                             CENTIMETRE MACHINE                                                                   TEST 7  TEST 8    TEST 9    TEST 10                                           in parts                                                                              in parts  in parts  in parts                                          by weight                                                                             by weight by weight by weight                                  ______________________________________                                        Polyol   100.00    100.00    100.00  100.00                                   Filler   0         15.00     20.00   25.00                                    suspension                                                                    Toluene  43.80     43.80     43.80   43.80                                    diisocyanate                                                                  Water    3.35      3.35      3.35    3.35                                     Catalyst 1                                                                             0.15      0.15      0.15    0.15                                     (DABCO)                                                                       Catalyst 2                                                                             0.30      0.30      0.30    0.30                                     (DMEA)                                                                        Catalyst 3                                                                             0.21      0.28      0.31    0.34                                     (stannous                                                                     octanoate)                                                                    Silicones                                                                              0.85      0.85      0.85    0.85                                     ______________________________________                                    

                  TABLE 4                                                         ______________________________________                                        MECHANICAL AND PHYSICAL CHARACTERISTICS OF                                    THE POLYURETHANES ACCORDING TO TABLE I                                                   TEST 3                                                                        Control                                                                              TEST 4   TEST 5   TEST 6                                    ______________________________________                                        Density in kg/m.sup.3                                                                      29.0     29.5     30.4   30.3                                    Indentation hardness                                                          (N)                                                                           25%          152      148      145    143                                     40%          183      180      177    174                                     65%          330      327      329    331                                     Compression                                                                   remanence in %                                                                *height difference                                                                         -1.2     -1.7     -1.7   -1.8                                    *hardness difference                                                                       -18.7    -19.7    -20.2  -20.5                                   Dynamic fatigue tests                                                         80,000×)                                                                *Δ height in %                                                                       -1.0     -1.5     -1.5   -1.5                                    *Δ hardness in %                                                                     -26.3    -27.7    -27.2  -26.7                                   Compressive strength                                                                       4.33     4.21     4.21   4.21                                    in kPa                                                                        Wet aging in %                                                                             -23.2    -13.5    -13.6  -13.6                                   Tensile strength in                                                                        91       107      104    98                                      kPa                                                                           Elongation at break                                                                        140      164      155    148                                     in %                                                                          Resistance to air flow                                                                     0.6      0.7      0.8    1.0                                     in mm of water                                                                S.O. quantity                                                                              0.187    0.312    0.326  0.344                                   ______________________________________                                    

                  TABLE 5                                                         ______________________________________                                        MECHANICAL AND PHYSICAL CHARACTERISTICS OF                                    THE POLYURETHANES ACCORDING TO TABLE 2                                                   TEST 7                                                                        Control                                                                              TEST 8   TEST 9   TEST 10                                   ______________________________________                                        Density in kg/m.sup.3                                                                      25.0     27.4     28.8   30.4                                    Indentation hardness                                                          (N)                                                                           25%          113      119      121    125                                     40%          137      144      149    153                                     65%          263      280      291    303                                     Compression                                                                   remanence in %                                                                *height difference                                                                         -2.4     -1.9     -1.9   -1.8                                    *hardness difference                                                          Dynamic fatigue tests                                                         80,000×)                                                                *Δ height in %                                                                       -2.0     -1.5     -1.5   -1.5                                    *Δ hardness in %                                                                     -29.6    -30.6    -30.1  -29.2                                   Compressive strength                                                                       3.45     3.61     3.72   3.88                                    in kPa                                                                        Wet aging in %                                                                             -7.9     -10.1    -9.7   -9.3                                    Tensile strength in                                                                        138      118      117    115                                     kPa                                                                           Elongation at break                                                                        252      208      208    205                                     in %                                                                          Resistance to air flow                                                                     1.1      0.95     0.97   0.97                                    in mm of water                                                                S.O. quantity                                                                              0.200    0.275    0.288  0.300                                   ______________________________________                                    

EXAMPLE 6

This example is an illustration of comparison between the mechanical andphysical characteristics of foamed polyurethanes:

Test 11 (control) without filler

Test 12, filled by means of the homogeneous and stable suspension of thefiller in the liquid organic phase according to the invention.

Test 13, filled by direct introduction of the pulverulent filler and ofthe liquid organic phase.

These tests were carried out on a Secmer pilot machine permitting thenoncontinuous manufacture of blocks 0.8×0.8×1.0 meter in size andevaluation of the mechanical characteristics which could be obtained ina process on an industrial scale.

The homogeneous and stable suspension according to the invention wasmade up of 60% by weight of pulverulent CaCO₃ (manufactured by the Omyacompany under the name Omyalite 60), dispersed in 39% by weight ofdiisoundecylenic phthalate in the presence of 1% by weight of astabilizing agent

    C.sub.10 H.sub.21 (CH.sub.2 --CH.sub.2 --O).sub.5 --PO.sub.3 H.sub.2.

The compositions used in the manufacture of the foamed polyurethanescontained qualitatively the following products:

diisocyanate: of Caradete 80 trademark from Shell

polyol: of Voranol CP 8322 trademark from Dow Chemicals

tin octanoate of Kosmos 29 trademark from Goldschmidt

DABCO 33 of Niax Catalyst A 33 trademark from Union Carbide

Niax Al from Union Carbide.

Dimethylethanolamine (DMEA) of Amietol M21 trademark from I.C.I.

Silicone: Thegostab BF 2370 from Goldschmidt

The quantities of the various constituents, expressed in parts byweight, are brought together in Table 6.

Similarly, all the mechanical and physical characteristics of thepolyurethane foams thus produced have been brought together in Table 7.These characteristics have been determined by means of the standardizedmethods which are listed in Example 5.

Analysis of these characteristics demonstrates that:

the indentation factor expressing the concept of comfort exhibitsequivalent values in Tests 12 and 13, which are higher than the controltest 11,

the tensile strength according to Test 13 is much lower than those ofthe control (Test 11) and of the invention (Test 12), which areidentical, whereas the elongation at break according to the invention(Test 12) is higher than Test 13 and than Test 11 (control).

the compression remanence in % if the case of the invention appearsbetter.

the density of the polyurethane foams of Test 12 and 13 is close to 40kg/m³ while the density of the control is lower. This higher density ofTests 12 and 13 can be brought back to the value of the control usingknown processes, such as a slight increase in the quantity of watersubjected to the corresponding quantity of isocyanate.

                  TABLE 6                                                         ______________________________________                                        Composition of the polyurethanes                                                                 Test 12                                                                 Test 11                                                                             according to                                                                             Test 13                                                      control                                                                             the invention                                                                            comparative                                     ______________________________________                                        Voranol CP3322 polyol                                                                        100     100        100                                         from Dow Chemicals                                                            Suspension of the filler                                                                     0       15         0                                           according to the invention                                                    Equivalent pulverulent                                                                       0       0          9                                           filler alone                                                                  Equivalent organic liquid                                                                    0       0          6                                           phase alone                                                                   Toluene diisocyanate                                                                         41.6    41.6       41.6                                        Water          3.2     3.2        3.2                                         Catalyst 1 (DABCO)                                                                           0.14    0.14       0.14                                        Catalyst 2 (DMEA)                                                                            0.08    0.08       0.08                                        Catalyst 3 (NIAXA1)                                                                          0.07    0.07       0.07                                        Union Carbide                                                                 Catalyst 4 (stannous                                                                         0.19    0.28       0.28                                        octanoate)                                                                    Silicone       0.90    0.90       0.90                                        ______________________________________                                    

                  TABLE 7                                                         ______________________________________                                        Mechanical and physical characteristics of the polyurethanes                  according to Table 6                                                                             Test 12                                                                 Test 11                                                                             according to                                                                             Test 13                                                      control                                                                             the invention                                                                            comparative                                     ______________________________________                                        Density kg/m.sup.3                                                                           32.7    39.5       40.2                                        Indentation hardness (N)                                                      25%            235     106        125                                         40%            305     168        188                                         65%            610     410        487                                         Indentation factor                                                                           2.59    3.86       3.89                                        Compression remanence in                                                                     8.6     6.3        7.3                                         % (height)                                                                    Compressive strength                                                          (kPa)                                                                         25%            6.37    2.96       3.39                                        40%            6.97    4.31       4.70                                        50%            8.16    5.35       5.94                                        65%            12.14   9.60       10.15                                       Tensile strength (kPa)                                                                       0.090   0.090      0.060                                       Elongation at break (%).                                                                     98      134        112                                         ______________________________________                                    

We claim:
 1. Process for preparation of filled, polyurethane-typeheat-curable compounds by means of the condensation reaction of theconstituents of the desired compound in the presence of a pulverulentfiller, wherein:a) said filler is predispersed in the presence of astabilizing agent introduced into a liquid organic phase compatible withthe desired heat-curable compound during its polymerization reaction,and in which said stabilizing agent present in the liquid organic phasehas the formula:

    R--(A).sub.m --(B).sub.n --X

containing at least one free acid function, in which X is a carboxylic,phosphinic, phosphonic, phosphoric, sulfonic, or sulfuric radical, (A)is ethylene oxide, (B) is propylene oxide, with 0≦(m+n)≦24, and where Ris selected from the group consisting of alkyl radicals, aryls,alkylaryls, saturated or unsaturated heterocycles containing from 5 to28 carbon atoms, and steroids; b) the homogeneous and stable suspensionof said filler prepared in this way is introduced into the reactionmixture before, during, or after addition of at least one of theconstituents of the desired heat-curable compound.
 2. Process accordingto claim 1, wherein the liquid organic phase is selected from the groupconsisting of dialkyl phthalates; symmetrical or asymmetrical, cyclicbranched or unbranched, aliphatic, aromatic, and glycol derivativedialkyl phthalates; and mixtures thereof.
 3. Process according to claim1, wherein the liquid organic phase is selected from the groupconsisting of dioctylphthalate, dibutylphthalate, dinonylphthalate,didecylphthalate, diheptylphthalate, diisodecylphthalate,diisoundecylphthalate, mixed octyl, butyl and decyl phthalates,benzylphthalate, cyclohexylphthalate, methyloxyethylphthalate,methyloxybutylphthalate, butoxyethylphthalate, and other glycol-basedsubstituents.
 4. Process according to claim 1, wherein the liquidorganic phase is selected from the group consisting of mono- orpolyalkyl, aryl, glycol-derivative phosphates.
 5. Process according toclaim 1, wherein the liquid organic phase is selected from the groupconsisting of polyesters.
 6. Process according to claim 1, wherein the Rradical of the stabilizing agent is selected from the group consistingof alkyl, aryl, and alkylaryl radical and saturated or unsaturatedheterocyclic ring which contains from 8 to 24 carbon atoms, and steroidradical.
 7. Process according to claim 1, wherein, when the X radical ofthe stabilizing agent contains several acid functions, at least one ofthese functions is free, the others being converted into salts oresterified by an alcohol corresponding to formula R'--OH, in which R' isselected from the group consisting of a carbon chain containing from 1to 4 carbon atoms and one of the radicals belonging to the groupspecified for R.
 8. Process according to claim 1, wherein the R radicalof the stabilizing agent contains at least one functional substituentselected from the group consisting of halogen, --OH, --COOH, --COOR,--NO₂, --NH₂, --CONH₂, phosphinic, phosphonic, phosphoric, sulfonic, andsulfuric type.
 9. Process according to claim 8, wherein the R' radicalis identical to the R radical.
 10. Process according to claim 1, whereinan additive selected from the group consisting of the reactioncatalysts, surfactants, thermal or photochemical stabilizers,lubricants, plasticizers, anti-static agents, fireproofing agents, metalpassivating agents, and expanding agents is added to the reactionmixture.
 11. Process according to claim 1, wherein the pulverulentfiller to be predispersed in the liquid organic phase is selected fromthe group consisting of mineral and synthetic pulverulent substances.12. Process according to claim 1, wherein the pulverulent filler to bepredispersed in the liquid organic phase is selected from the groupconsisting of naturally-occurring and synthetic pulverulent organicsubstances.
 13. Process according to claim 1, wherein the pulverulentfiller is a combination of naturally-occurring mineral and syntheticpulverulent substances.
 14. Process according to claim 1, wherein thepulverulent substances forming the filler have a dimension of between0.01 and 300 μm.
 15. Process according to claim 1, wherein thehomogeneous and stable suspension of the filler is composed, in relationto total weight, of:a) 20% to 80% by weight of the filler; b) 79.9% to18.4% by weight of the liquid organic phase; and c) 0.1 to 1.6% byweight of the stabilizing agent.
 16. Process according to claim 1,wherein a polyalcohol capable of being used to produce the desiredheat-curable compound is added to the homogeneous and stable suspensionof the filler.
 17. Process according to claim 1, wherein the Brookfieldviscosity of the homogeneous and stable suspension is between 500 and2000 mPa.s measured at ambient temperature.
 18. Process according toclaim 1, wherein the homogeneous and stable suspension of the filler isintroduced into the composition of the desired polyurethane compound inthe proportion of from 1% to 100% by weight of the polyalcohol used. 19.Process according to claim 1, wherein the liquid organic phase isselected from the group consisting of trioctylphosphate,tricresylphosphate, octyldicresylphosphate, and other alkylarylphosphates.
 20. Process according to claim 1, wherein the liquid organicphase is selected from the group consisting of ethylene glycol,propylene glycol polyadipates and ethylene glycol or propylene glycolpolysebacates.
 21. Process according to claim 1, wherein the pulverulentfiller to be predispersed in the liquid organic phase is selected fromthe group consisting of calcium carbonate, zinc carbonate, dolomite,chalk, magnesium oxide, aluminum trihydroxide, silica, clays, kaolin,talc, mica, zinc, iron, antimony, and titanium oxide, glass fibers andballotini, wollastonite, organic or inorganic pigments, red phosphorus,and mixtures thereof.
 22. Process according to claim 1, wherein thepulverulent filler to be predispersed in the liquid organic phase isselected from the group consisting of coloring agents, carbon black,starch, cellulose fibers or flour, carbon fibers, melamine powders, andmixtures thereof.
 23. Process according to claim 1, wherein thepulverulent substances forming the filler have a dimension of between0.1 and 100 μm.
 24. Process according to claim 1, wherein thehomogeneous and stable suspension of the filler is composed of:a) from40% to 70% by weight of the filler; b) 50.5% to 28.9% by weight of theliquid organic phase; and c) 0.5% to 1.1% by weight of the stabilizingagent.
 25. Process according to claim 1, wherein the Brookfieldviscosity of the homogeneous and stable suspension is between 600 and1600 mPa.s measured at ambient temperature.
 26. Process according toclaim 15, wherein the homogeneous and stable suspension of the filler isfirst mixed with the polyalcohol in order to form a premix, this premixbeing then mixed with the other constituents and wherein all of theconstituents are used in the quantities and proportions defined asrequired.
 27. Process according to claim 1, wherein the stable andhomogeneous suspension of the filler is added simultaneously to thevarious constituents of the desired polyurethane and wherein all of theconstituents are used in the quantities and proportions defined asrequired.
 28. Process according to claim 26, wherein the homogeneous andstable suspension is introduced into the reaction mixture afterpreparation of the premix of all of the constituents of the desiredpolyurethane and wherein all of the constituents are used in thequantities and proportions defined as required.
 29. Process according toclaim 1, wherein said process is applied using known techniques intendedfor the manufacture of heat-curable compounds of the polyurethane type.30. Homogeneous and stable suspension of a pulverulent filler in aliquid organic phase to be used in the preparation of filledheat-curable compounds of the polyurethane type wherein said liquidorganic phase is compatible with the desired heat-curable compound andwherein said filler is predispersed in the presence of a stabilizingagent which has the formula containing at least one free acidicfunctional group:

    R--(A).sub.m --(B).sub.n --X

in which X is selected from the group consisting of carboxylic,phosphinic, phosphonic, phosphoric, sulfonic, and sulfuric radical, (A)is ethylene oxide, (B) is propylene oxide, with 0≦(m+n)≦24, R isselected from the group consisting of alkyl radicals, aryl radicals,alkylaryls, saturated or unsaturated heterocyclic rings containing from5 to 28 carbon atoms and steroid radical.
 31. Process according to claim1, wherein the liquid organic phase is selected from the groupconsisting of esters of organic or inorganic poly or monoacids;alkyladipate, alkysebacate; diesters of trimellitic, azelaic, abietic,citric, mellitic, stearic, oleic, palmitic, ricinoleic, myristic,benzoic and pelargonic acid; and C-1 to C-8 alcohols of mono, di, ortriethylene glycol and glycerol.